Oxidative stress in bacteria (Pseudomonas putida) exposed to nanostructures of silicon carbide Andrzej Borkowski a,⇑ , Mateusz Szala b , Pawel Kowalczyk c , Tomasz Clapa d , Dorota Naro _ zna e , Marek Selwet d a Faculty of Geology, University of Warsaw, _ Zwirki i Wigury 93, 02-089 Warsaw, Poland b Faculty of Advanced Technologies and Chemistry, Military University of Technology, Kaliskiego 2, 00-908 Warsaw, Poland c Bionicum Ltd., Chelmska 21, Warsaw, Poland d Department of General and Environmental Microbiology, Poznan University of Life Sciences, Szydlowska 50, 60-656 Poznan, Poland e Department of Biochemistry and Biotechnology, Poznan University of Life Sciences, Dojazd 11, 60-632 Poznan, Poland highlights  Silicon carbide nanostructures were produced by combustion synthesis.  Oxidative stress in Pseudomonas putida was investigated.  Peroxidase activity, expression of zwf- 1 gene and cell viability were analyzed.  SiC nanofibers and nanorods can induce oxidative stress in P. putida. graphical abstract article info Article history: Received 12 December 2014 Received in revised form 10 April 2015 Accepted 17 April 2015 Keywords: Silicon carbide Nanofibers Nanorods Oxidative stress Pseudomonas putida Toxicity abstract Silicon carbide (SiC) nanostructures produced by combustion synthesis can cause oxidative stress in the bacterium Pseudomonas putida. The results of this study showed that SiC nanostructures damaged the cell membrane, which can lead to oxidative stress in living cells and to the loss of cell viability. As a reference, micrometric SiC was also used, which did not exhibit toxicity toward cells. Oxidative stress was studied by analyzing the activity of peroxidases, and the expression of the glucose-6-phosphate dehydrogenase gene (zwf1) using real-time PCR and northern blot techniques. Damage to nucleic acid was studied by iso- lating and hydrolyzing plasmids with the formamidopyrimidine [fapy]-DNA glycosylase (also known as 8-oxoguanine DNA glycosylase) (Fpg), which is able to detect damaged DNA. The level of viable microbial cells was investigated by propidium iodide and acridine orange staining. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction A review of the literature shows that nanomaterials can be cyto- and genotoxic to prokaryotic and eukaryotic cells. Most of the tests on nanostructures were run with one- and two dimension http://dx.doi.org/10.1016/j.chemosphere.2015.04.066 0045-6535/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: a.borkowski@uw.edu.pl (A. Borkowski). Chemosphere 135 (2015) 233–239 Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere